Adsorption of Phenol from Aqueous Solution Utilizing Activated Carbon Prepared from Catha edulis Stem

Phenol and its derivatives in water and wastewater are highly toxic and challenging to degrade, posing serious environmental and health risks. Therefore, this research focuses on the removal of phenol from aqueous solutions using activated carbon made from Catha edulis stems. The activation process involved impregnating the Catha edulis stems with phosphoric acid followed by thermal treatment at 500 °C for 2 h. The resulting adsorbent was extensively characterized using various techniques, including Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), Brunauer–Emmett–Teller (BET) surface area analysis, and proximate analysis. Batch adsorption experiments were designed using a full factorial approach with four factors at two levels, resulting in 16 different experimental conditions. The characterization results showed that the activated carbon has a high surface area of 1323 m²/g, a porous and heterogeneous structure, and an amorphous surface with multiple functional groups. Under optimal conditions of pH 2, a contact time of 60 min, an adsorbent dosage of 0.1 g/100 mL, and an initial phenol concentration of 100 mg/L, the adsorbent achieved a phenol removal efficiency of 99.9%. Isotherm and kinetics analyses revealed that phenol adsorption fits the Langmuir model and pseudo-second-order kinetics, indicating a uniform interaction and chemisorptive process. This study highlights the effectiveness of Catha edulis stem-based activated carbon as a promising material for phenol removal in water treatment applications.